The spinal column acts as a major structural support. Various mechanisms, however, affect the ability of intervertebral disks to provide the requisite stability and support. For example, the normal aging process tends to weaken the bones and tissues associated with the spinal column increasing the risk of spinal injuries. Additionally, sudden movements may cause a disk to rupture or herniate. A herniation of the disk is primarily a problem when the nucleus pulposus protrudes or ruptures into the spinal canal placing pressure on nerves which in turn causes spasms, tingling, numbness, and/or pain in one or more parts of the body, depending on the nerves involved. Further deterioration of the disk can cause the damaged disk to lose height and to produce bone spurs. These mechanisms may result in a narrowing of the spinal canal and foramen, thereby causing undesired pressure on the nerves emanating from the spinal cord.
Treatments of spinal cord conditions include various procedures which involve the removal of all or a portion of a spinal component. Such procedures may include the injection of an enzyme into an affected disk to dissolve tissues. The enzymes typically used in this procedure are protein-digesting enzymes which must be carefully placed with respect to the spinal defect to avoid inadvertent dissolution of spinal tissue.
Alternatively, surgical access to a spinal area may be obtained and a tool such as a curette, osteotome, reamer, rasp, or drill may be used to mechanically reshape a component of the spinal column. The tissue removed may include disk tissue which is causing pressure on a nerve or the spinal canal. This technique is highly invasive and traumatic to the body, and therefore requires an extended recovery period. Moreover, there are increased risks of future problems due to the removal of a portion of the lamina which is no longer in place to support and protect the spinal canal at the area where the surgery took place.
Surgical access may also be used for spinal fusion surgery. In a fusion procedure, a damaged disk may be completely removed. Parts of a bone from another part of the patient's body, such as the pelvis, are harvested, and the bone parts or grafts are subsequently placed between the adjacent vertebrae so that the adjacent vertebrae grow together in a solid mass. The recovery time for a normal spinal fusion surgery is significant due not only to the fact that normal movement cannot be allowed until detectable bone growth has occurred between the bone grafts and the adjacent vertebrae, but also due to the fact that the associated ligaments and muscles, both at the spinal location and the location where the bone grafts were harvested, must also recover.
Recently, efforts have been directed to replacing defective spinal column components. When this type of procedure is performed in a minimally invasive manner, it is known for various devices implanted during the procedure to be subsequently expelled from the intervertebral disks. This expulsion is frequently attributed to inadequate clearance of the nucleus during the minimally invasive surgical procedure. The result is that the interdiskal device extrudes from the cavity formed in the spinal column, increasing the potential for expulsion.
A need exists for a device for loosening tissue that is minimally invasive, easy to use, and safe. A further need exists for a device which provides for both the loosening of tissue and the removal of loosened tissue. A further need exists for a device which can be used to determine the amount of loosened tissue that has been removed.